Automatic starting regulator for overload release devices



Dec. 30, 1952 c. A. HENNESSY 2,624,032

AUTOMATIC STARTING REGULATOR F OR OVERLOAD RELEASE DEVICES Filed Dec. 4.1950 CARROLL A. HENNESSY Fl 6. 4 INVENTOR ATTORNEY Patented Dec. 30,1952 AUTOMATIC STARTING REGULATOR FOR OVERLOAD RELEASE DEVICES CarrollA. Hennessy, Syracuse, N. Y., assignor to Lamson Corporation, Syracuse,N. Y., a corporation of New York Application December 4, 1950, SerialNo. 199,033

8 Claims.

This invention relates to an automatic starting regulator for overloadrelease devices in connection with machine drives, and more particularlyto a regulator which compensates for the starting inertia of the drivenmachine and also provides for automatic release of the machine upon aninitial overload.

Certain machines, conveyors in particular, re quire an overload releasedevice to shut off the Power or to decrease the speed of the machinewhen the machine becomes jammed or otherwise overloaded. In many cases,the starting inertia of the machine is as great, or greater than, thepermissible load on the machine under operating conditions. a startinginertia greater, in many cases, than the permissible overload while theconveyor is moving. Materials, such as cartons and light articles,carried by the conveyor, are frequently easily damaged should theybecome jammed in some way in the conveyor. This necessitates setting theoverload release device so that the conveyor is stopped when only aslight overload on the drive of the machine occurs.

Some long conveyors require several driving units along their length,and the speed of the several drives must be synchronized so that eachdriving unit bears its proportionate share of the load. Such conditionsmake it difiicult to start such a conveyor safeiy, since the overloadrelease device or devices should be set to stop the driving motors upona comparatively small overload.

, The present invention is designed and has for its principal object toautomatically regulate the overload release devices of such machines sothat they may be easily started without manually resetting the overloadrelease device each time the machine is started.

A further object is to provide overload release means to stop themachine should it become jammed or more than usually overloaded duringstarting.

. Another object is to provide easily installed and synchronizedstarting regulators for machines with multiple drives and multipleoverload release devices.

. Other objects and advantages will more fully appear from the followingdescription, taken in connection with the accompanying drawing, inwhich:

Figure 1 is a diagrammatical side elevation of a machine drive, overloadrelease device, and starting regulator, together with control means;

Figure 2 is a plan view of the overload release Long conveyors inparticular have 2 device and starting regulator of Figure 1, partly insection on the line 22 thereof;

Figure 3 is a diagrammatical plan view of a single drive unit of amultiple drive machine, together with an overload release anddrivesynchronizing device, a modified form of starting regulator andcontrol means; and

Figure 4 is a fragmentary side elevation of the mechanism shown inFigure 3.

Referring more particularly to Figures 1 and 2, the drive and overloadrelease device, more fully described in United States Patent 1,949,119to William J. Gibbs, comprises an electric motor Hi, driving a reducer il, which, in turn, drives the shaft 12 of a conveyor or other machine,by means of an endless driving member l3, such as a belt or chain, anddrive elements, such as pulleys or sprockets l4 and IS. The overloadrelease device includes a bell-crank l6 secured to a shaft I? which ispivotally supported by pillow block bearings I8-l8. Arm 19 of thebell-crank 16 has a sliding weight 20 adjustably secured thereto. Arm 2icarries a rotary idler member 22, such as a pulley or a sprocket,adapted to contact the driving side of the endless drive member 13 androtatably secured to arm 2| by shaft 23. Bell-crank to has a contact arm25 projecting therefrom and adapted to contact lever 26 of limit switch21 as the bell-crank is turned. Switch 21 is connected in series in theelectric supply wiring 28 to motor ID. A control switch is indicated at29 in Figure 1.

The starting regulator mechanism comprises a supplementary weightedlever 39, a solenoid 3| and a pneumatic timing relay 32 wired inparallel with switch 27. Lever 38 is a lever of the third orderpivotally supported at one end by the clevis 33 and pin 34 to swing in asubstantially vertical plane. A sliding weight 35 is adjustably securedto the lever 30, and the free end of the lever is adapted to overhangand rest on the free end of arm [9 of bell-crank [6. Intermediate theends of lever 39, a link 36 joins the lever to the plunger of thesolenoid 3|, which is shown as of the pull type.

The solenoid 3| is energized by the pneumatic timing relay 32, which isshown as including a solenoid G0 operatively connected to diaphragmbellows 4|. One side of the diaphragm is connected to an adjustablebleeder valve 42, and movement of the solenoid plunger operates a limitswitch 43. The timing relay 32 is of a commercially well-known type, butit will be apparent that it may be replaced by any combination of timingdevice and electrical relay which is adapted to energize the solenoid 3!a suitable number of seconds after the turning on of current to motorIll.

The operation of the overload release device depends on the tension onthe endless driving member [3. As the load on the machine driven byshaft [2 increases, the increased tension on the drive member [3 movesthe rotary idler member 22 and bell-crank it toward the position shownin broken lines at lea, lifting the weighted arm 19. When the loadreaches an amount for which the device has been set by adjustment ofweight 23 on arm is, the contact arm 25 breaks the circuit throughswitch 21, shutting off power to the motor Hi.

It will be apparent that, in many machines such as conveyors, it will benecessary to set this overload release device so that a very slightoverload will stop the conveyor. This is necessary to prevent damage tothe material or packages, carried by the conveyor, when they becomejammed in some manner. In long conveyors, the starting inertia of theconveyor parts will exceed the amount of permissible overload.

To start such a machine, the starting regulator lever 3% is weighted bysliding and securing weight 35 in such a position as to compensate forthe starting inertia of the machine. Lever St is then allowed to restupon arm l9. Assuming that control switch 29 is open and switch 27 hasbeen manually closed, switch 29 is now closed, causing motor Iii to beenergized. The additional weight of lever 3i compensates for thestarting inertia of the machine and the overload release device isprevented from shutting oil the power to the motor while it is starting.Any more than usual load on the machine during starting, caused byjamming or otherwise, will be added to the normal starting inertia'andwill cause arm id to rise, pushing lever 30 before it, and switch 27will be turned off in the usual manner.

When no overload occurs in starting, motor it is started and reaches itsnormal running speed usually in an interval on the order of 3 toseconds. The pneumatic timing relay 32 is therefore set for thisinterval by adjustment of the bleeder valve 42. When the circuit tomotor H] is closed, solenoid 56, being in parallel with the motor, isalso energized. The plunger of solenoid H3 pushes against the diaphragmii and rises as air is bled from the valve 42. At the end of this 3 to 5second interval, the plunger has risen sufficiently to close switch '13,thus energizing solenoid 3i. When solenoid 3| is energized, it pulls thelever 38 upward away from arm I9 to the position shown in broken linesat 3th, leaving the overload release device free to operate in normalmanner.

When the machine is turned off, by reason of the operation of eitherswitch 2? or switch 29, current to the motor and hence to solenoid 3! isshut off. Arm l9 swings down, and, as it is always under lever 33, lever36 drops upon it. Gravity, or preferably a return spring, resets thepneumatic timing relay 32.

It will now be apparent that the starting inertia of the machine may bethus automatically compensated for, without disturbing the normaloperation of the overload release device, and with provision being madefor overload release during starting.

Figures 3 and 4 illustrate a modified form of automatic startingregulator. A conveyor, or other machine, may be driven in a conventionalmanner by shaft 5%], by means of motor 5!, re-

ducer 52 and an endless drive member 53, such as a chain or belt,connecting the sprockets or pulleys 54 and 55 on reducer 52 and shaft50, respectively. A variator 56, or speed-changing device, such as thevariable diameter pulley device described in United States Patent583,402 to M. O. Reeves, may be interposed between motor 5| and reducer52 in the conventional manner.

An overload release device, similar to the one described above, includesthe bell-crank Bil pivotally supported at 6| on the reducer or thesupporting frame of the machine. One arm of bellcrank 6d carries therotary idler member e2, such as a sprocket or pulley, adapted to contactthe driving side of the endless drive member 53. The other arm ofbell-crank 66 is pivotally connected to a clevis 63 at one end of aconnecting rod 64. The other end of rod 64 is pivoted to a weightedlever t5 intermediate the ends thereof. One end of lever 65 is securedto a shaft 86 rotatably supported by a pillow block bearing 6'1. Theother end of lever E35 bears a weight 58 slidable thereon and ad ustablysecured thereto. Bell-crank (iii and lever 65 are thus linked togetherto move toward the positions shown in broken lines at tea and 650.,respectively, as the tension on the endless drive member 5:3 isincreased, and bellcrank til is weighted by the action of weight .68 onlever 65. A spring-pressed idler sprocket or pulley 59 may contact theother side of the endless member 53 to keep it taut.

A limit switch is is supported by the frame of the machine so that itsoperating lever TI is in the path of bell-crank 68, and the circuitthrough the switch is broken when the bell-crank reaches the positionindicated at 69a. Switch Ill is connected in series with the controlswitch 12 in the electric supply 'Wiring ":3 to motor 5|.

The starting regulator comprises an air-operated piston and cylinder l5,an air supply line it, certam valves connected thereto as hereinafterdescribed, and an electrical relay ll wired in parallel with theelectric supply line 13 to the motor.

The air cylinder 15 is supported by the frame of the machine in such aposition that the contact plate :8 borne by the piston rod of its pistonl9, when fully extended by air introduced into the cylinder as indicatedat 1817 and 7%, will oppose and obstruct the movement of bell-crank 63away from the normal running position shown in full lines. A stop may besecured to the frame of the machine to limit the movement of bell-crank69 as shown. Return springs 8|8 extend from plate 78 to cylinder i5.

Air is supplied to the cylinder l5, behind the piston, throughappropriate piping from the supply line 76. Air from the supply linepasses first through a conventional low pressure regulator valve 82 andthen through a standard in-line, direct, solenoid-operated, 3-way valve83. This valve is spring operated, when its solenoid 84 is notenergized, to allow free passage of air from its entrance port 87 to itsexit port 85, and the exhaust port 85 is blocked. When solenoid 84energized, the entrance port 8'! is blocked and free passage of air fromthe exit port 85 is allowed to the exhaust port 36. The exit port 85,which is always open, is connected to the conventional needle valve 88,which is connected to a conventional safety, or pop, valve 89, which, inturn, is connected to cylinder 15.

Solenoid 84 is energized from an ele-ctrical'supply line 90, preferablyof lower voltage than the line 73, by means of the relay 17 as shown.

The overload release device shown in Figures 3 and 4 may also be used toregulate the speed of the machine drive shown. Certain large machines,such as long overhead conveyors, require several motors and drives atintervals along their length so that the whole driven load will not beborne by the whole length of chain or belt which runs the length of theconveyor. By having multiple drive units each section of the conveyorbears only a portion of the load. When multiple drives are used, thespeed of each drive unit must be regulated, the speed of each drivebeing decreased, when the load on that unit becomes unduly great, sothat the other drive units may take up their share of the load.

The drive unit shown in Figure 3 may be used as one of a number of suchmultiple drives, the variator 56 being used in well-known manner tocontrol the speed of the drive. The end of shaft 66, opposite the end towhich is secured the swinging lever 65, has secured thereto the spurgear 9|. A smaller gear 92 is in mesh with gear 9|, as shown in Figure4, gear 92 being secured to a shaft 93 which is journalled in thepillow-block bearing 94 and to which is also secured the sprocket 95.Sprocket 95 drives the sprocket 66 by means of chain 97, the lattersprocket controlling the speed ratio of the pulleys of variator 56 inwell-known manner.

The overload release device of Figures 3 and 4 operates like the onepreviously described in connection with Figures 1 and 2. As the load onthe conveyor or other machine increases, the tension on the driving sideor" the endless drive member 53, increases, moving the idler 62 andbell-crank 60 toward the position shown at 68a. Should the load becomeso great that the position 66a is reached, the limit switch 70 isoperated by reason of bell-crank 66 striking the switch lever ll.Current to the motor 5| is thereby cut off.

Should the load on the drive move bell-crank 60 only slightly, and notall the way to the position shown at 60a, lever 65 is raised toward theposition shown in broken lines at 65a and gear 9| is rotated. Gear 92 isalso rotated, causing the sprockets 95 and 96 to turn and reducing thespeed of the drive. This allows the other drive units of the conveyor,or other machine, to pick up more of the total load and lessen the loadon the drive unit here shown. Stop 88 is positioned to hold lever 69 andthe weighted lever 65 in such position as to maintain the maximumdesired speed.

When switch 16, or control switch 12, is turned off, the current tomotor 5| is interrupted, as is the current to relay ll, which is inparallel with motor 5|. Relay 11 being de-energized, the circuit tosolenoid 84 is interrupted, and valve 83 allows air to flow from thesupply line '16, through regulator valve 82 and the entrance port 81 andexit port 85 to the needle valve 88. Exhaust port 86 is closed. Airpasses through the needle valve 88, through valve 89, into cylinder 15and pushes the piston 19, without shock, to its extended position at1917. Contact plate 18 is pushed into the path of, and immediatelyadjacent, bell-crank 60 at 181), lever 69 resting against stop 88 byreason of the pull of the weighted lever 65. Air remains under pressurein cylinder 15 as long as motor 5| is turned ofi.

Switch 18 being manually reset, if necessary, the motor 5| is started byturning switch I2 on. Switch 12 may control the motors of all thedrives, if multiple drives are used. As motor 5| starts, the load on theconveyor, or other machine,

including the inertia of starting, puts tension on the drive side of theendless drive member 53, tending to move bell-crank 68 toward theposition 60a. Movement of bell-crank 60 is blocked during the startingof motor 5|, however, by the plate 18 at 18b.

With the closing of switch 72, however, relay 7! is energized, closingthe circuit to solenoid 84 of valve 83. The plunger of valve 83 isthereby moved to cut off the entrance of air through port 87 and theexit port 85 is connected to the exhaust port 86. Air under pressure incylinder 15 may then bleed out through the needle valve 88 and throughthe ports 85 and 86 of valve 83. As the air bleeds out of cylinder 15,the plate 78 is moved away from lever 60 by the return springs 8|-8|.Needle valve 88 may be adjusted so that plate 18 may be withdrawn duringthe 3 to 5 second interval during which motor 5| is reaching its normalrate of speed, the inertia of starting being compensated for only duringthis period of starting.

Any unusual overload during starting may still out out motor 5| byopening switch 10, by reason of the action of pop valve 89. This valveis set to open and release air to atmosphere should the pressure incylinder 15 increase over the pressure of normal starting caused bypressure of bell-crank 66 on plate 18.

When plate '58 has been withdrawn after the interval of starting, theoverload release mechanism again assumes its normal role of regulatingthe speed of the drive by adjustment of the variator 56 and of acting asa safety cut-out when bell-crank 66 trips the switch 18.

When the current to motor 5| is out off by switch 72 or switch I6, relay1'! is again de-energized and current to solenoid 84 is again out off.Valve 83 thereupon connects ports 85 and 81 and blocks the exhaust port86. Air is again allowed to flow into cylinder 75, and plate 78 isextended to 18b immediately adjacent bell-crank 66, ready for restartingmotor 5|.

When the drive unit shown in Figures 3 and '4 is used as one of a numberof similar drives in a multiple drive machine, the starting regulatorsof all the drive units may be synchronized by the adjustment of theirrespective needle valves 88. Each valve 88 may be adjusted so that thetime interval for the exhausting air from cylinders 15 is approximatelyequal. As air is exhausted from the cylinders 15 during the starting ofthe motors, the plates 18 of each unit will be gradually withdrawnallowing the speed regulating devices 56 to be increasingly efiective indistributing the load as the starting interval elapses.

It will be apparent to those skilled in the art that the startingregulator l5-'|'l'|883- 88-89 of Figures 3 and 4 may be substituted forthe regulator 30-3|32 of Figures 1 and 2 by positioning the air cylinderso that plate 18 is directed downward to contact the free end of arm IS.The regulator 383|32 may also be substituted in Figures 3 and 4 bypositioning the lever 30 so that it falls downward into the path of theweighted lever 65. The device shown in Figures 1 and 2, however, hasbeen found particularly satisfactory for vertical conveyors, while thatof Figures 3 and 4 is particularly satisfactory for substantiallyhorizontal conveyors such as overhead conveyors.

In all the figures of the drawing, the supporting framework has not beenshown, fragmentary portions only being shown to indicate the fact ofsuch support. It will also be apparent that the figures of the.dremingeshow the drives andslnrerloadi release devicesiaindiagrammatical tf-ashion and that Ldilieren't arrangements of :parts:may equally well'ibe made. Spring-loaded .levers,.for instance,..:maybe substituted for the gravityloaded levers of the drawing, andthestarting reguiatorsmay equally welllbe used with :difierentarrangements of the levers viand linkages.

1 ,While there xissherein idescribed, andrin the drawingshown,.:illustr.ative embodiments of :the i-uventi'onritds .ito.sbeiunderstood that the invent'i'on'ismotslimitedmhereto, :butmaycomprehend other constructions, arrangement "of parts, detailazandfeatures without departing from the spirit of Ithe invention; .I desireto be .jlimited. thereforeionly :by "the scope of the appended claims.

1. The combination "iwitha irnacblne drive, ineluding :a" motor 1 and anendless driving member, and can overload ;release device having a loafed bell-crank rotatable in response to theztension on said endlessdriving member and operably connected to control saidmotoriresponsive-to:said tension, of supplementary means foraddditionallyresisting the turning of said bell-crank when the motor .isstarted, said supplementary meanslbeingremovableirom thempath of saidbell-crank at a predetermined tension .on sai endless driving member,andtimed means for removing xsaid supplementary means irom the path "ofsaid bell-crank after a predetermined timerfrom the starting ofsaidmotor.

2. .The combination with driving .mean's,' ineluding a motor, a drivenmachine, an endless driving -:member connecting said driving means andsaid machine, and anoverload release device including a loadedbell-crank, a rotary idler contacting said endless driving member andmounted on an armof saidbell-crank, whereby themovementtof saidbell-crank is responsive to the .tension'on :said endless drivingmember, the movement of said bell-crank controlling said drivinggmeans,offlan automatic starting regulator comprising supplementary means .foradditionally resistingithec-movement'of said loaded bell-crank, meansifor iiyieldingly interposin'g said supplementary means in the path ofsaid bell-crank upon thestoppingof the motor to compensate for :thesucceeding starting inertia of saiddriven machine,r imeans. forwithdrawing said supplementary-means from the path ofsaid bell-crank,andftimingmm'eans for initiating the withdrawal of: saidisupplementarymeans at a predetermined time after theistarting of the motor.

3. An automatic starting regulator for machine-drive overload releasedevices having a loadedlever moving in response to the load on saidmachineand thereby controlling said drive, comprisinga second loadedlever guided to fall upon, and augment the 1oad-on,said first loadedleverrvhen the machine-drive is stopped, means for lifting: said secondlever from the path of said firstijlever, and timed means 1 forinitiating the liftingl'of said second lever from thep'ath of thefirsti'aiter afpredetermined' time from the startingofts'aidmachine-drive, said-second lever being loaded to substantiallycompensate for the starting inertia of said machine whereby said secondlever may be lifted by said first lever upon-any initial overloading ofsaid machine.

au'tomatic starting regulator 'for machine-drive overload-releasedevices having a ioadedllevertmovinginresponse to the load on themachine andrthereby controlling :said drive,

comprising at-second loaded; lever .gnidedtd normallyzrest :upon said.overloadereleaseiierer and to :augment the. load thereon .:tosubstantially compensate for the starting :inertiaof;said;machine,asolenoid energized .by thestarting ofsaid machineedriveand operably connected to .said second clever to .lift it from the.first lever, and timing .meansiorzdelaying the energizing of :saidsolenoidiora predetermined timeafterathestarting of said.;machine-drive.

15. ."automatic starting; regulator :for-amachine-drive overload-release:clevices :having :a loaded clever moving vinresponse .to the load :onsaid machine and thereby controlling said drive. comprising a contactplate fluid-nperated:means for vextending said plate against:and;.opposed'?to the movement .ofrsaid overload-releaselever, ea sourceof .iiuid. .under'ipressure, "valve :means frfor normally csupplyingfluid .;under pressure tozisaid fiuideopaerated Lmeans, ;:spring meansopposed .to said. fluid-operated o'means ior withdrawing LSBii-d contactplate from .the vpath of :said .1ever,.ivalve means operatedcoincidentally with. theistarting of said machine drive .for cutting. onthe supply of .fiuid and fertile timed escape .of .iiuid from saidfluid-operated means, whereby saidcontact plateis .withdrawnirom thepath .of theooverload releaselevenafter the starting :inertia -o'f themachine has been overcome, andasafetyvalve connected to said.fluid-operated means for theimmediate escape of fiuidtherefromnponanyinitial overloadexceeding thenormal startinginertia of the machine.

.An automatic starting regulator for (machine-drive :overload-releasedevice's having a loaded lever movingin response to the load on saidmachine and thereby controlling saiddrive, comprising anaha-operatedpiston-and cylinder, a source oiair under pressure, valvemeans for normally supplying'air under pressure .to said cylindennmeansoperated coincidentally with the starting tor" said machine-drive forcutting ofl said supply and allowing the timedescapeofair from saidcylinder, a contact plate extensible by the operation of said pistontoopposethemovemerit of said loaded lever, resilient means forWithdrawingsaid plate, and asafety valveconnected to said cylinder,whereby the starting inertia of said machine is compensated for by theopposition of said plate during the starting of saidmachine-drive.

7-. .An automatic starting regulator for marchine-drive overload-releasedevices having a loaded lever moving in'response to the load on said:machine and thereby oontrollingsa'id drive, comprising an air-operatedpiston and cylinder, a contact plate operable by said pistonand cylindertoextend intothe path of said lever to prevent .:the normal operation ofsaid overloadrelease caused by the starting inertia of said machine,.resi'lientmeans for withdrawing said .ZCOH-' tact plate from the'pathof the lever,-a'-source of air lunderpressure, valve means fornormally-sup plying-air under pressure to said cylinder, means operatedby the starting of said machine-*d-r'ive for operating said valve meansto out off the supply of'air to the cylinder, an adjustable bleedervalve for thetimed exhausting of air'from the cylinder whereby the airmay be exhausted during the interval in which starting inertia ispresent, and a pop valve connected to saidcylinderf-or the immediateexhausting of air therefrom 'upon an initial overload on said machine.

8.. An automatic starting regulator for machineedriveoverloadereleasedevices having-a loaded lever moving in response to the load on themachine and thereby controlling the machine drive, comp-rising anair-operated piston and cylinder, a source of air under pressure, athreeway valve, a needle valve and a pop valve, said source of air beingconnected to said cylinder through said valves, said three-way valvenormally allowing air to flow to the cylinder through said needle valve,a solenoid energized upon the starting of said machine drive andoperably connected to said three-way valve to shut off the supply of airand to allow air to bleed from the cylinder through said needle valvewhen the solenoid is energized, said needle valve being adjustablewhereby the air may be exhausted from the cylinder at a predeterminedelapsed time from the starting of the machine drive, a contact plateoperated by said piston to oppose the movement of said loaded lever whenthe piston is extended 10 by air under pressure in the cylinder, springmeans for Withdrawing said contact plate from the path of the lever whenair is exhausted from the cylinder, and said pop valve being adapted toimmediately exhaust air from the cylinder upon an initial overload inexcess of the normal starting inertia of the machine.

CARROLL A. HENNESSY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,9a9,119 Gibbs Feb. 27, 19342,085,115 McShane June 29, 1937 2,305,391 Rosenmund Dec. 15, 19422,329,280 Lunken et a1 Sept. 14, 1943

